Does continuous ST-segment monitoring add prognostic information to the TIMI, PURSUIT, and GRACE risk scores?

BACKGROUND: Recurrent ischemia is frequent in patients with non-ST-elevation acute coronary syndromes (NST-ACS), and portends a worse prognosis. Continuous ST-segment monitoring (CSTM) reflects the dynamic nature of ischemia and allows the detection of silent episodes. The aim of this study is to investigate whether CSTM adds prognostic information to the risk scores (RS) currently used.
METHODS: We studied 234 patients with NST-ACS in whom CSTM was performed in the first 24 hours after admission. An ST episode was defined as a transient ST-segment deviation in ≥1 lead of ≥ 0.1 mV, and persisting ≥1 minute. Three RS were calculated: Thrombolysis in Myocardial Infarction (TIMI; for NST-ACS), Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Supression Using Integrilin (PURSUIT; death/MI model), and Global Registry of Acute Coronary Events (GRACE). The end point was defined as death or nonfatal myocardial infarction (MI), during 1-year follow-up.
RESULTS: ST episodes were detected in 54 patients (23.1%) and associated with worse 1-year outcome: 25.9% end point rate versus 12.2% (Odds Ratio [OR]= 2.51; 95% Confidence Interval [CI], 1.18-5, 35; P = 0.026). All three RS predicted 1-year outcome, but the GRACE (c-statistic = 0.755; 95% CI, 0.695-0.809) was superior to both TIMI (c-statistic = 0.632; 95% CI, 0.567-0.694) and PURSUIT (c-statistic = 0.644; 95% CI: 0.579-0.706). A GRACE RS > 124 showed the highest accuracy for predicting end point. The presence of ST episodes added independent prognostic information the TIMI RS (hazard ratio [HR]= 2.23; 95% CI, 1.13-4.38) and to PURSUIT RS (HR = 2.03; 95% CI, 1.03-3.98), but not to the GRACE RS.
CONCLUSIONS: CSTM provides incremental prognostic information beyond the TIMI and PURSUIT RS, but not the GRACE risk score. Hence, the GRACE risk score should be the preferred stratification model in daily practice. ©2011, Wiley Periodicals, Inc.